Acidosis and 5-(N-ethyl-N-isopropyl)amiloride (EIPA) Attenuate Zinc/Kainate Toxicity in Cultured Cerebellar Granule Neurons.

Cultured cerebellar granule neurons (CGNs) are resistant to the toxic effect of ZnCl2 (0.005 mM, 3 h) and slightly sensitive to the effect of kainate (0.1 mM, 3 h). Simultaneous treatment of CGNs with kainate and ZnCl2 caused intensive neuronal death, which was attenuated by external acidosis (pH 6.5) or 5-(N-ethyl-N-isopropyl)amiloride (EIPA, Na+/H+ exchange blocker, 0.03 mM). Intracellular zinc and calcium ion concentrations ([Zn2+]i and [Ca2+]i) were increased under the toxic action of kainate + ZnCl2, this effect being significantly decreased on external acidosis and increased in case of EIPA addition. Neuronal Zn2+ imaging demonstrated that EIPA increases the cytosolic concentration of free Zn2+ on incubation in Zn2+-containing solution. These data imply that acidosis reduces ZnCl2/kainate toxic effects by decreasing Zn2+ entry into neurons, and EIPA prevents zinc stores from being overloaded with zinc.

Delayed action of serotonin in molluscan development.

Serotonin (5-HT) is known to induce a wide range of short-term and long-term (or delayed) effects. In the present paper we demonstrated that short time-window application of the 5-HT precursor 5-hydroxytryptophan during early cleavage stages results in both irreversible morphological malformation (exogastrulation) and distinct changes in behavior of young animals of the freshwater snail, Lymnaea stagnalis (Mollusca: Gastropoda). Pharmacological and immunocytochemical analysis confirmed that both the increase of intracellular 5-HT level within the cleaved blastomers and activation of membrane 5-HT2-like type receptors are required for the appearence of these phenomena.

Serotonin transport and synthesis systems during early development of invertebrates: functional analysis on a bivalve model. Short communication.

Serotonin (5.HT) is known to be functionally active during early development in both vertebrates and invertebrates. However, the presence of 5-HT and its synthesis and transport system has not yet been demonstrated in bivalve early development. The presence of 5-HT was immunochemically demonstrated at the cleavage stage of bivalve Mytilus trossulus. 5-HT level dramatically increased within all embryonic cells after incubation with 5-HTP but not after incubation with tryptophan and 5-HT. The first 5-HT uptake by specific transporter was detected at 13 hpf blastula stage only and it was restricted to one distinct cell.

Modulation of Mytilus trossulus (Bivalvia: Mollusca) larval survival and growth in culture. Short communication.

Commercial importance and ability to live in a wide range of salinities have made the common mussel, Mytilus trossulus, a relevant model to study modulation of larval growth and development. We investigated the effects of various salinities combined with neomycin and ampicillin application on Mytilus larvae survival and growth. Both neomycin and ampicillin enhanced trochophore and veliger survival under condition of low salinity. The average veliger size was increasing in accordance with the increase of salinity. In case of neomycin treatment 3.6% of the larvae reached the pediveliger stage. No abnormalities of larval morphology of the FMRFamide and 5-HT systems occurred after 7 days of culturing with both antibiotics.

[Morphogenetic consequences of partial removal of blastomere cytoplasm during early embryonic development of the loach, Misgurnus fossilis L].

The development of loach embryos is successfully regulated (normalized) after partial removal of the cytoplasm from one blastomere at the two- or four-cell stage or complete removal of one or two blastomeres at the stage of 8-16 cells. Using time-lapse video imaging and morphometric analysis, it has been shown that this regulation is a two-stage process. At the first stage, the ratio between the volumes of the blastodisk and yolk sac is rapidly (within one or two cell cycles) restored almost to the initial level; at the second stage, morphogenesis of the embryo is modified according to its new structural features acquired after the operation. After several rounds of cytokinesis, the cytoplasm remaining in the operated blastomere fuses with the marginal yolk syncytium (periblast),which at the blastula stage forms a distinct extension at the operation site. This extension marks the site of embryonic shield formation. The results of morphometric analysis show that restoration of the initial blastoderm volume in operated embryos leads to a reduction of active tension at the blastoderm--yolk boundary and an increase in the ratio of blastoderm surface to its volume at the moment of epiboly initiation. As a result, the convergence of blastoderm cells to the operation site and the embryonic shield formation begin at a lesser degree of epiboly, compared to the control.

[Postspawning survival in lacustrine sock-eyed salmon Oncorhynchus nerka Walb].

The state of gonads, age, structure of scales, and size of specimens of the resident lacustrine form of sock-eyed salmon--kokanee Onchorhynchus nerka--are analyzed. In stocked, previously fishless, lakes, there are specimens that have survived spawning and have remained active for a year or several years. No evidence was found of the possibility of repeated spawning. Thus, such fish do not belong to the spawning stock of the population, and their ecological function is not clear.

[Pioneer neurons: a basis or bottleneck of diversity of nervous systems of Lophotrochozoa?].

In a case study on development of larvae of Trochozoa species of different systematic positions, it was shown that peripheral neurons differentiated firstly. According to the characters of early peripheral neurons, in particular their localization in parts that differed from known zones of appearance of central ganglia, the difficult periphery of processes used as a "frame" by differentiated neurons of definitive nervous system, and transient expression of specific markers, it is reputed that these cells are pioneer. On the one hand, pioneer neurons are the bottleneck of morphogenesis diversity in late stages of development which prepare, in early larvae, the framework of the further central nervous system. On the other hand, navigation and marking using pioneer neurons can be a mechanism of evolutionary lability of definitive neural structures. Functional adaptive significance of pioneer neurons of larvae of Trochozoa animals, probably, is in the maintenance of a fast change from larvae life-form to adult life-form in metamorphosis that decreases the time of animals at intermediate stages of morphogenesis, which are associated with a dramatic fall in adaptation.